What Are the Different Kinds of Ticks?

Ticks are parasitic arachnids that feed off the blood of a host animal. They breed worldwide in most climates, and can spread Lyme disease and Rocky Mountain spotted fever, among other illnesses. Hundreds of varieties exist, but only a few are a threat to humans and pets.

Deer Tick

• Deer ticks are about the size of a sesame seed. When they become engorged with blood, however, they can swell to 1/4 inch in diameter. The male is all black, while the female has a red abdomen. Their favorite hosts are deer, but they will also attach themselves to cattle, horses and dogs. They will attack humans, but it is generally by accident. Deer ticks are a primary source of Lyme disease, which causes flu-like symptoms and joint pain.

Brown Dog Tick

• The brown dog tick is difficult to distinguish from the deer tick, but it poses less of a health threat. The male and female are almost identical -- reddish-brown and about 1/8 inch long. When engorged, the female can swell to 1/2 inch. This tick rarely attaches itself to humans; dogs are its primary target. The brown dog tick does not spread any known diseases.

American Dog Tick

• Unlike the brown dog tick, the American dog tick poses a serious health threat: It is a primary carrier of Rocky Mountain spotted fever, which is potentially lethal if left untreated. The American dog tick is reddish-brown and about 1/4 inch long but can swell to 1/2 inch after feeding. Its primary targets are mice, birds, raccoons, dogs and humans.

Lone Star Tick

• The Lone Star tick is a small variety -- adults are about 1/8 inch long -- that attaches itself to large mammals, including deer and horses. This tick is brown, but the female has a white spot on her back. An aggressive tick, it is similar in appearance to the American dog tick. It too can transmit Rocky Mountain spotted fever, as well as tularemia and ehrlichiosis, but it is not believed to transmit Lyme disease.